If empty

I’m loading some info by an mysql database into flash. I created a variable for the web site
var Site:Object = this.Membre.Siteweb … And It working perfectly. With that variable I’m able to load the web site and make some action. The only problem is there is not always a web site, when there is not a web site I would like to make an if/else and when the site is empty do thing but else thos some function (on release on a picture and on some text.)

How?

Thx
Xelaxa